High-speed sheet feeding without grip pliers

ABSTRACT

The invention concerns a conveying device for sheet steel plates and for moving several sheets ( 1, 1 ′) inside or through a working zone (W;  50 ) wherein the sheets are machined. The inventive feeding device comprises first and second sheet feeders ( 10, 11; 20 ) which feed the sheets in controlled manner to the working zone (W) so that the sheets are machined with positional accuracy. The first sheet feeder ( 10, 11 ) is located on an input side of the tool zone and the second sheet feeder ( 20 ) is located on an output side of the tool zone. The two sheet feeders ( 10, 20; 11; 20 ) are mutually synchronized in their movements (x, y) when feeding forward the sheet ( 1 ), the sheet driven by the synchronous movement being maintained by the two sheet feeders. The invention provides the advantages of increased speed and safety. It is possible to increase the speed without the sheet being deformed or losing its flatness.

This invention relates to a sheet feeding device and a respective methodfor feeding sheets to a working zone where the sheets are machined. Themachining may include a punching operation in which rounds are punchedout of the sheet and arranged in close proximity due to a remaining gridon the sheet. This invention also relates to a belt drive whererevolving belts handle the sheet feed function.

The starting point is state-of-the-art sheet feeders, where grip pliersare used to grip the rear end, i.e., the edge of the sheet facing awayfrom the tool area to convey the sheets over a feeder table which isstationary into the tool area and thereby position it with an indexingmovement in x and y directions so that the rounds can be cut out of thesheets by rams arranged close together in a row. The rams here have agreater distance than the centers of the rounds on the sheets, so that alateral movement of the sheets in relation to the rams is necessary toensure the density of the arrangement of the rounds and to minimize theresidual grid that remains after punching out the shapes. In addition,to the density of the arrangement of the rounds, production speed isalso a significant influencing factor for the cost of manufacturingwhich is to be minimized.

One approach in the state of the art is to provide two grip pliers whichalternately one after the other convey sheets into the tool zone wherethe front grip pliers perform a return stroke oriented in the ydirection when the next following grip pliers enter with the next sheetinto the tool zone. A quasi-continuous conveyance may be achieved inthis way although the sheets are positioned individually (see GermanUtility Model DE-U 296 23 908 (Naroska), page 5, second paragraph).

Another implementation from the state of the art is directed at usingonly a single plier which after its forward movement performs a rapidreturn movement in the y direction and then grips the new sheet that hasbeen selected and positioned on the rear (edge) which follows and isfacing away from the tool zone, advancing the sheet into the tool zone.Because of the high speed, synchronization problems may occur in thetransfer of the sheet from a loading area via a table transfer positioninto the feed area, thus preventing higher speeds. In addition, thepliers used in both state-of-the-art approaches are the reason why astrip zone at the rear end area of each sheet cannot be machined afterthe force required for the movement has been applied by gripping in aspot application of the pliers (in the sense of a small point of actionfor the clamping force of the pliers in comparison with the area of thesheet). Thus if the strip area (usually also referred to as plier trim)is to be minimized as much as possible, then punching out the last rowof rounds will involve an increased safety problem if the pliers extendinto the tool zone and are thus very close to the punching or embossingrams.

Therefore the object of this invention is to increase the speed ofconveyance from the state of the art while gaining safety and at leastretaining the benefits (i.e., the useful area of the punched-out roundsin comparison with the total area of the sheet), but preferablyincreasing it.

This object is achieved with a conveying device according to claims 1, 5or 15 and/or 17 having a belt conveyor device according to claim 10 or amethod of conveying sheets according to claims 23, 30 or 22.

This invention eliminates the need for using tongs or grippers or pliersfor the purpose of conveying the sheets. This also eliminates the spotapplication of the forward conveyance force on the rear end, i.e., theedge section of the sheet which is facing away from the tool. Instead ofthat, the force is essentially applied over a flat area, e.g., in alinear or strip pattern to the sheet to feed it into the tool zone by anindexing action (claim 5).

The continuous systems to be used for this purpose, in particularcontinuous systems designed with belts, are revolving drive belts whichare arranged side-by-side in a plane in the form of strips supportingthe sheets with their surfaces on a longitudinal section and thuspermitting a drive over almost the full area although they themselvessupport the sheets to be conveyed (claim 8).

An essentially continuous conveyance without requiring the punchingdevice to execute learning strokes in a regular punching cycle isachieved by means of two sheet feeders arranged one above the other,whereby an essentially flat holding function is exerted on the surfaceof each sheet. A sheet is supplied in suspension while the other sheetis lying on the tool zone. A transverse gap formed between the sheetsthus conveyed is so small in the longitudinal direction that it ispossible to speak of an alternating supply of individual sheets which ispractically continuous as seen from the standpoint of the tool (claim1).

To apply holding power to the sheets, belts having magnetizable surfacesmay be used (claim 10). Alternatives to applying the force may includeusing a reduced pressure when the surfaces of the belts of the sheetfeeds have openings with which a tensile force (as a holding force) canbe applied to the sheets.

Advantages of this invention include a possible increased speed and thesafety that is gained. Safety is increased because the pliers acting onthe rear are omitted. Speed can be increased without the sheets beingdeformed out of their planar position, a condition that is verydifficult to meet with plier feed acting on the rear and an increasedspeed. In addition, times can be shortened and the risks entailed insynchronization in synchronizing the sheets at the beginning of theforward movement with the pliers are eliminated.

The “usage” of a sheet may also be increased because in contrast withthe previous plier strip, no strip area need be left unmachined here.The yield (usage) can be increased and more freedom is gained in designof the tool machining the sheets.

Experiments regarding the essentially flat support of the sheets haveshown that over 300 cycles per minute can be achieved based on apunching device as the tool in the working zone.

Safety and a lower susceptibility to trouble are improved by the factthat a stationary supporting table which supports the sheet in itsforward feed by the pliers according to the state of the art is nolonger necessary and thus unevenness, residual sheet metal particles orirregularities on the surface of this conveyor table are eliminated.However, the conveyor table according to this invention moves with thesheet; it is formed by a plurality of individual continuous systems,each applying holding or supporting force to the sheet independentlyover the surface along a longitudinal section of its longitudinalextent.

Since the continuous belt systems have a top strand and a bottom strand,any cleaning of the surface may be performed on the bottom strand whichdoes not come in contact with the sheets.

According to this invention, another sheet feed may also be provided inthe output of the tool zone (claims 17 and 20). When using just onesheet feed, this may be the second sheet feed. However, if two sheetfeeds are used one above the other at the input side, then the thirdsheet feed is used according to this invention. This feed, which isarranged downstream from the tool in the direction of travel y, operatesin synchronization with the feed mechanism situated upstream from thetool. This synchronous motion pertains to the indexing movements whichoccur in directions y and x (main direction y) so that the sheets areguided by the tool upstream and downstream from the tool are part oftheir movement through the zones—upstream from the tool by holding thesheet, downstream from the tool by the transfer of the remaining grid,for example, after the punching device has punched out the rounds. Theforward feed is thus composed of a pushing force and a pulling force ina plane of through-travel consisting of the inlet plane, the outletplane and the working table surface of the machine tool.

Due to the fact that the conveyor device is provided on the output side,it is possible to machine the sheets up to the end of the rear edge sothere need no longer be a strip shape remainder where in the state ofthe art so far the pliers have applied their holding force.

In the conveyor method (claim 22) both the input side and the outputside may be provided with an uneven edge which results with a mutualalignment of the rounds due to the offset of the center points to permitmaximum utilization of the sheet metal. At the same time with this sheetfeed, the lateral movement may also be shortened in the incrementalindexing of the sheet during its forward feed with the edge on the frontend and on the rear end of each sheet being trapezoidal in shape, forexample, based on the direction of conveyance y. A shortened lateralmovement results in the machining being performed more rapidly and moremachining devices, in particular more punching or pressing rams can beaccommodated in a given width. If in the state of the art so far atransverse offset of the next row of rounds to be punched outtransversely oriented row is provided, then according to this inventiona linear front of rounds is no longer necessary. In the longitudinaldirection there is an offset of an entire adjacent column of roundswhich are aligned with their midpoints in the longitudinal direction (inthe direction of conveyance y, without an offset).

Working strokes executed by the forward feed are thus instead combinedin a zigzag pattern without any exclusive lateral transverse movementsbut instead combined by an x movement and a y direction in the forwardfeed and/or a lateral direction thereto in order to approach the nextposition for machining in a controlled manner.

EXEMPLARY EMBODIMENTS ILLUSTRATE AND SUPPLEMENT THE INVENTION

FIG. 1 shows a top view of a first example of a feed mechanism for aflat sheet 1 which is to be machined with an input feed 10, 11 and anoutput feed 20. They are adjacent to a working zone W which is to beassumed below is a punching device 50.

FIG. 2 shows a view of the working device W to illustrate its functionand with the upper feed device 10 removed at the input so that only thebottom feed device 11 can be seen at the input with the sheet metal 1placed on it and the conveyor device 20 at the output.

FIG. 3 illustrates the end of the input advance device pointing towardthe working zone W with the upper feed 10 and the lower feed 11.

FIG. 4 shows a side view of the input conveyor device where the conveyorlevel or the input level 100 can be seen.

FIG. 5 shows a front view of the conveyor device at the output, also theoutput conveyor device 20 as seen from the working zone W.

FIG. 6 shows a side view of the output conveyor device 20 with its frontend defining the output plane 100 which is a continuation of the inputplane of FIG. 4 and corresponds to the surface of a machining sheet 52of the working device as shown in FIG. 2.

FIG. 7 shows a detail of a conveyor belt in Example 10a and its internalstructure.

FIG. 7 a shows a section perpendicular to the section in FIG. 7, where alateral guidance of the conveyor belt of FIG. 7 is shown.

FIG. 8 shows a schematic diagram of a sheet 1 as conveyed toward thepunching device by the conveyor device according to the previousfigures, showing printed or drawn rounds R which are punched out by thepunching device 50.

The first exemplary embodiment according to FIG. 1 shows a combinationof the components used. A conveyor device 10 above and a similarconveyor device 11 which is not visible below that are each equippedwith multiple parallel continuous belts, namely in the example shownhere 10 belts 10 a through 10 k arranged side-by-side in this example.The middle belt 10 e is shown symbolically. This conveyor device isaligned with a working zone W which in this example is formed by apunching device 50 which extends transversely. Downstream from the toolis a conveyor device 20 having a design similar to that of the conveyordevice 10. It is partially covered by a discharge system 29 with theinner conveyor belts. Here again in this example, ten conveyor belts arearranged closely side-by-side as continuous systems labeled as 20 athrough 20 k. Here again, the conveyor belt 20 e has been shownsymbolically as the longitudinal continuation of the input conveyor belt10 e.

The input conveyor devices 10, 11 as the first sheet conveyor mechanismsand the output conveyor device 20 as an additional sheet feed mechanismare arranged in the input and output areas respectively with respect tothe tool 50.

The direction of conveyance y here is the longitudinal direction. In thetransverse direction x, there is a row of working rams in the tool 50,as shown by FIG. 2. The rams 50, which are aligned here in a row andhave individual punching rams 50 a, 50 d and 50 e, operate insynchronization at a high frequency of up to 300 working strokes perminute corresponding to a working frequency of 5 Hz. The main directionof conveyance y is the direction of forward travel or the longitudinaldirection. The continuous belt systems 10 a through 10 k, 11 a through11 k and 20 a through 20 k are shown in mutual proximity in thetransverse direction x in FIG. 1; the adjusting stroke used to positionthe sheets also occurs in the transverse direction x.

FIG. 1 also shows the input area of the input sheet transport 10, 11with two stacks of sheets L1 and L2 arranged on both sides of analignment station A with an H-shaped alignment and supporting device.The sheet metal here is first unstacked from one side, placed on thealignment station A (from the side) and then there is an aligningoperation which aligns the sheet metal just supplied so that it isaligned correctly in relation to the tool 50 at the working point Wafter being supplied to the conveyor device 10, 11. When one stack L1 isdepleted, the second stack of sheet metal placed on the other side ofthe alignment station A can be accessed directly, with the sheet metalnow being unstacked from it and sent to the alignment station A cominglaterally from the right. The alignment station A is followed by aswitch plate 9 which is pivotable about an axis to influence the heightdirection or height position of the aligned sheets coming from thealignment station. To do so, the switch plate 9 is pivotable by a smallangle which is synchronized with the forward feed of the current sheetout of the alignment station and into the sheet conveyance systems 10 or11. The axis here is closer to the alignment station and the free end ofthe switch plate results in a slight upward deflection of a sheet feedwhen pivoted upward. If the switch plate is inclined out of its restingposition or slightly downward, the sheet is supplied from the alignmentstation to the lower sheet conveyance system 11 without any change inheight.

The survey diagram in FIG. 1 should illustrate which components come tolie in which location with respect to the tool device 50 in the workingzone W. The function is to be described on the basis of FIG. 2 in whichthe upper sheet conveyance system together with its revolving belts 10 athrough 10 k have been omitted for the sake of simplicity and a sheet 1rests on the lower continuous conveyor system 11 with its parallel belts11 a through 11 k. The sheet stack L1 and L2 as well as the alignmentstation A have been omitted here and the tool 50 is shown in a schematicview so that its punch rams 50 a through 50 e which work on the insideare discernible.

A discharge system 29 which removes the rounds that have been punchedout of the sheet in the transverse direction q along a path 30 isarranged downstream from the punching rams 50 a through 50 e of thepunching device 50. Therefore the multiple rounds which are punched outat the same time are moved from the location of the punching ram in themain direction of conveyance y using pulsating compressed air in shortblow-out channels and at the end of the short y channel segments 31 athrough 31 e the rounds are conveyed together with a magnetic transverseconveyor belt 33 to a supporting device 32 which moves laterally in saidtransverse direction q which runs in parallel with the x direction. FIG.5 gives a view into the channel segments 31 a through 31 e. These areextensions of the punching rams 50 a that are aligned in the ydirection. If other working devices which do not work with punching ramsare used at the working location W then the discharge system may beomitted, e.g., when the working location is used only for printing thesurface of the sheet, i.e., the rounds are left physically connected tothe sheet.

The revolving belts 11 a through 11 k are driven in synchronization. Adrive device 18 which is used for this purpose can be seen with a flangeconnection on the side; it applies a torque to a shaft 18 w whichgenerates a rearward deflection with deflection pulleys and generatesthe drive of the continuous belts. After positioning the sheet above thealignment area A in FIG. 1, the sheet is transferred to the bottom sheetconveyor 11 while the switch is lowered, and then it runs in the ydirection with a longitudinal movement of the conveyor belts 11 athrough 11 k until it is a defined distance in front of the toolposition W. The sheet 1″ here is stopped in the position “waiting” whichis detected by at least one sensor 28. In this waiting position, thesheet waits until a sheet conveyed before it and also machined by thetool has been conveyed completely to the tool through the conveyordevice which is situated above it to then be inserted seamlessly, i.e.,without a blank stroke of the rams 50 a through 50 e moving up and downinto the first punching position of the sheet 1 shown here, labeled as1′. From this time on the sheet moves by a displacement and indexingmotion in both the y direction and in the x direction so that all thegiven rounds as shown on a sheet in FIG. 8 as an example are punched outby the five punching rams shown here.

In doing so, this sheet is advanced over a machining table 52, the planeof which corresponds essentially to the plane 100 formed by the surfacesof the conveyor belts on which the sheet 1 comes to rest in the insertedposition and in the first punching position.

The indexing movement is prompted by a drive 17 which is mountedlaterally and is controlled so that the position is accurate by acontrol unit (not shown), where y forms the main direction of conveyancefrom left to right in FIG. 2; this is handled by the movement of thebelts 11 and these belts are also controlled by a control unit so thatthe respective positions of the rounds beneath the rams are determinedaccurately. When the position for machining has been reached, theconveyor movement in both x and y directions is turned off and the ramsare engaged. After moving the rams out of the sheet, a new indexingmovement begins, composed of a combination of an x step and a y step forreaching the next position.

As shown by the subsequent side views, the indexing movement in the xdirection is prompted in such a way that the entire conveyor device isdisplaced in the x direction, which effects all the belts 11 a through11 k simultaneously and in synchronization. Because of the commondriveshaft 18 w, the movements in y direction are also insynchronization and simultaneously, triggered by the motor drive 18which induces a controlled rotation in a drive roller via a slip-freedrive belt 18 a, with a sliding bearing being provided for the shaft 18w in the axial direction. The shaft 18 w is axially movable in the driveroller but is not movable in the circumferential direction. Such a shaftmay be designed for example as a grooved shaft or as a polygonal shaftin a pinion that is axially displaceable in a pinion to reduce theweight that must be moved with the conveyance in the x direction. Onlythe shaft 18 w is moved here but the motor 18 and the respective drivebelt 18 a are not in motion.

The output in FIG. 2 shows multiple parallel continuous systems 20 athrough 20 k of the sheet feed mechanism 20 where the longitudinalmovement of the device in the y direction is also performed by a drive26 which is flanged onto the side and has a belt transfer 26 a andpulley 26 b on a shaft 26 w which is arranged on the end of the secondsheet feed device 20 which faces away from the punching device. Hereagain, an indexing movement is possible and is performed in the same wayas the indexing movement of the sheet feed 11 on the input side but hereis performed by a drive 27 on the output side.

In the indexing movement, all the revolving belts on the input side aremoving in the x direction in synchronization with those on the outputside. The movement is also synchronized in the y direction so that thesheet 1 is not only held in the input but also in the output and canmove into the tool on the one hand while on the other hand it can bepulled out of the tool on the output side. Therefore the output side isalso to be understood as a type of feed mechanism with an effect on thesheet section which is still on the input side. However, only theremaining grid remains on the output side after the rounds have beenpunched out of the full area sheet on the input side but thisconstitutes a physical connection and thus is not capable oftransmission of forces. If instead of the punching device anothermachining device is selected for the working zone W, then the sheet mayalso still be in complete form, e.g., if only printing or a surfacecoating is performed which does not make any changes in the mechanicalconsistency of the sheet as a whole.

The side view shows schematically how the work table 52 belongs togetherwith the punching device in the working zone W where the input conveyorbelt 11 is shown with parallel continuous systems and an output conveyorsystem 20 which also has multiple parallel continuous systems. This sideand the other side of the table border these continuous systems and arein close contact with the work table 52 which may be designed with aslight inclination to receive the sheet 1 which is shown schematicallyin the feeding motion when the continuous conveyor system 11 conveys thesheet at the inlet according to the y direction. The conveyor plane 100which corresponds essentially to the surface of the belts is also shownin all three components 11, 52, 20 but it may also come to lie in theplane of a sheet metal 1 that has just been conveyed or it may be formedby the surface of the table 52.

To be able to guide the sheets with forces which act at a right angle tothe direction of conveyance y and to the indexing direction x, whichhere is assumed to be in the z direction, these sheets are designed witha special surface. FIG. 7 shows a special example.

The revolving conveyor belt 10 a is shown here in a detail and in asectional view. A belt base 62 is shown with a reduced thickness incomparison with that of a conventional conveyor belt and it is equippedwith teeth 61 on the side facing inward, these teeth being provided atan essentially uniform distance in the longitudinal direction y. Acorresponding toothed roll engages between these teeth from thedriveshaft side so that multiple adjacent conveyor belts do not show anyslippage in relation to one another.

On the outside, i.e., the surface of the conveyor belt 10 a facingtoward the sheet 1, a magnetic layer 63 is applied; in the exampledepicted here this is a film which is attached by an adhesive layer 64to the outside surface of the base of the belt 62; it is filled withmagnetic particles or is designed as a permanent magnet film. It has aheight of <1 mm, in particular in the range between 0.1 and 1 mm, tomaintain the elastically and flexibility of the belt but at the sametime it forms essentially a flat surface on the surface to offer apossibility of holding metallic sheet metal by magnetic adhesion forcein the z direction and guiding such sheets in a controlled fashion inthe y direction.

Other exemplary embodiments of a conveyor belt for applying adhesiveforce in the z direction include those equipped with flow openings ornozzle openings to apply a force through a vacuum.

The revolving belts according to FIG. 7 are illustrated again in asectional view in the x direction in FIG. 7 a. Here again the magneticlayer 63 has been provided, moving in the y direction (vertically out ofthe plane of the paper) for conveyance purposes to the sheet 1 which isshown schematically in FIG. 7. To permit an essentially planar surfaceon the length of the belt and so that the belt sags little or none atall in the longitudinal direction, a lateral guidance 65 a, 65 b isprovided for the base 62 of the belt which is held by the lateral guidesin the z direction in areas 62 a and 62 b. The guides are designed asU-shaped rails or sections which protrude more inward in the x directionbeneath the belt than above. Above the belt the thickness of the trackis adapted essentially to the thickness of the magnetic layer 63 so thatan essentially uniform surface is created over the entire transversedirection b₁₀ of the belt and the lateral guidance. If the magneticlayer 63 protrudes slightly in height with respect to the guides, so itis elevated with respect to them, the friction of the sheet metal on thelateral longitudinal guides 65 a, 65 b is reduced.

To simplify the design of the belt, the toothed sections 61 are alsoincluded by the lateral U-shaped guides 65 a, 65 b. In the driving areawhere the teeth are to either serve the purpose of slip-freetransmission of the movement of the shaft 16 w, 18 w or 26 w and thecorresponding driving pinions, the belts lie freely without any lateralguidance.

The back of the belt 62 is greatly reduced in comparison with the usualbacks of toothed belts, with the height of the teeth 61 being greaterthan the thickness of the back of the belt. Instead of a design withteeth, another design of the belt on the inside may also be selected ifan essentially slip-free transmission of the movement of the driveshafts 18 w and/or 26 w is possible. It should be taken into accounthere that the driveshaft 18 w exerts a pushing movement on the belts 11a through 11 k, i.e., is at a greater distance from the working zone Wthan a deflecting shaft 18 v which is arranged close to the worktable52. A lateral guidance is less critical for the output belt 20 and mayoptionally be omitted because there is a forward movement here due to apulling movement on the parallel belts 20 a through 20 k there, with thedeflector shaft 26 v close to the working table 52 having only adeflection function with respect to the direction of movement and nothaving any driving function. However, if the drive device in the workingzone W can be designed in such a way that it takes up less space or if apunching device with a different division of space can be used, then adrive device on the shaft 18 v may also be selected for the continuousconveyor system 11 so that lateral guides may also be omitted here ifthe length of the belt allows this to prevent sagging.

The sheets machined with the device according to FIG. 1 and in thefunction diagram of FIG. 2 may be used for the case when the punchingdevice 50 is used to produce the rounds R with which metal closures forglasses for wide-neck bottles can be manufactured. Even during thepunching operation, a shape may be imparted to the rounds by a deepdrawing process so that a peripheral skirt edge is imparted to them;this skirt is later provided with a sealing agent and with wearing camsso it can serve as a bottle closure. This starts with round forms whenthe closures are to be applied by a rotating movement but it is alsopossible to use other rounded forms that do not have a rectangular orsquare design. Because of their shape, the coverage or filling of thesheet is a significant factor in determining the “usage” in the sense ofthe greatest possible utilization of round areas based on the totalsheet area.

The sheet shown in FIG. 8 has a plurality of rounds in close proximity,with a certain alignment of the rounds to one another being provideddepending on the direction of observation. In this example a movement y′of the sheet from the right to left should be assumed for the state ofthe art and from above in the direction y for the use in the sheet feedaccording to FIG. 1. On the top and bottom sides, the sheet has acorrugated pattern which may be shaped in a trapezoidal form or may berounded (so-called “scroll edge”). The front edge 1 v and the rear edge1 r form the input edge and the rear end edge respectively for thedevice according to FIG. 1, the latter being the last to pass throughthe machining device W. The side edges 1 d and 1 e are designed to besmooth and straight. They run parallel to a respective grid line throughthe center of rounds aligned in rows in the y direction. In onedirection perpendicular to the side edges 1 d, 1 e are formed rowslabeled as R1, R2, R3, R4 through Rn. The first row R1 is the row thatenters the tool device 50 first at the working point W as shown in FIG.2.

To save on sheet area, the columns of rounds, each oriented in the ydirection, are each offset by a half distance from the center of theadjacent row so that the curvatures of the rounds can be situated closetogether. This results in a first row R1 of rounds on the front edge 1 vwhich are not close together but instead have a definite distance in thex direction which is labeled as c in the first and second rows R1, R2.This distance is greater than the distance between the two grid linesrunning in the x direction, i.e., the distance separating them in the ydirection. These comparative grid lines result from joining the centersM of the first and third rows of rounds in the x direction.

If the sheet with its scrolled (jagged or wavy or not straight) frontend 1 v is moved into the machining device 50, all the rounds of row R1at the front are machined in one working stroke of the press 50 whichmoves the punching rams. Because of the greater distance c, it is nolonger necessary for the rams to be arranged in such a way that there isnot a pure transverse displacement in the x direction for finishing themachining of the first row and an indexing movement toward the next rowR2 may take place as a shorter and faster movement than if there firsthad to be a lateral movement in the first row R1 to machine any roundsmore closely arranged there in a second working stroke.

Eliminating this machining step in the state of the art is apparent whenFIG. 8 is rotated by 90° and the edge 1 d is regarded as the edge whichenters into the tool device 50 in the y′ direction (corresponding to thex direction in the example according to this invention). The rounds ofthe first row here (parallel to edge 1 d) are so close together that therams of the tool which require a greater distance can only machine everysecond round. A pure lateral movement is necessary to punch out thesecond rounds which could not be machined in the first working stroke.

For such a movement, the gripper locations 2 a, 2 b shown with dash-dotline would be used as they are used in the state of the art on a stripGTR having the width b. This direction of advance labeled as y′ is thesame as that in the state of the art, but it can be seen here that thegripper area at the edge 1 e is very small in comparison with the totalarea of the sheet 1, but the width b of the strip serves to the benefitof the whole.

If the need for still having a strip area for gripping purposes iseliminated according to the conveyor device described here, then with aconveyance movement in the y direction (FIG. 8 in the originalalignment) the strip on the right having a width b can be reduced tosuch an extent that it is also discernible on the left edge 1 d.Consequently a sheet metal strip of the sheet material can be saved thatwould not otherwise be used constructively (to form rounds).

It can also be seen that the density of rounds is also unchanged incomparison with the state of the art, i.e., the usage has not beenincreased by merely reducing the strip width b, increasing the speed byeliminating an x indexing movement in a first row R1 and by the greaterspacing of the centers in each row Rn of rounds so that more rounds aremachined as flat pieces in one working stroke and in particular can bepunched out than when the rounds are closer together.

Since rounds are used here as an example and need not necessarily becircular in shape, it is also possible to speak of flat pieces which areto be arranged on the sheet in such a way as to permit maximum usage ofthe useful area of the sheet with the least possible remaining webportion which is determined in width by the edge areas of the flatpieces which are closest together and by the properties of the machiningtool, e.g., the punching device which requires a predetermined minimumresidual web to be able to make a clean cut.

It was mentioned previously that a (imaginary) connecting line betweenthe centers of the third row R3 and a connecting line between thecenters of the first row R1 is used to determine their distance “d.”This necessarily presupposes that there is a second row of rounds inbetween whose centers can be imagined as connected by a connecting lineto form a second connecting line between the first and third connectinglines. This is at a distance d/2 from the first and second connectinglines.

If the distance c measured in the x direction from the centers in afirst row of rounds is compared with the distance of the third grid linerunning in the x direction, this refers to the next-but-one grid line.When a uniform and/or orthogonal network is drawn in where all theconnecting lines of all the centers running perpendicular to one anotherare shown, this yields a denser network line geometry in the y directionthan in the x direction. The new forward feed makes use of this and usesthe greater distances between the centers in the x direction to allowthese rounds to be machined at the same time by the tool device 50 inthis front (row).

In supplementing the function of the continuous conveyance of sheets,the side views and front views of the arrangement in FIG. 1 areillustrated in greater detectable in FIGS. 3 through 6, where it can beseen in the input area of FIG. 3 that a gap 12 is formed between anupper sheet feed 10 and a lower sheet feed 11 as shown in FIG. 4. Thisgap is greater than the thickness of one sheet 1 as shown in FIG. 8 andas placed on the lower sheet feed 11 in the input area in FIG. 2. Theside view in FIG. 4 shows a wedge-shaped belt guide for the upperconveyor belts [10] and the lower conveyor belts 11. It is elongated andaligned with the tool area W which is represented by the input plane 100which comes to lie in the gap 12. The two opposite conveyor beltsections in gap 12 of the continuous conveyor belts aligned in parallelare equipped with the magnetic surface as illustrated in FIG. 7. Theupper feed 10 can be raised with a lifting device 19 out of two liftingcylinders 19 a, 19 b which are a distance apart so that the upper feed10 is raised in relation to the lower sheet feed 11.

The two sheet feeds 10 and 11 are each movable as a whole in the xdirection in a controlled manner, which is achieved by drive 15 for theupper sheet feed and by drive 17 for the lower sheet feed 11, with thesheets moving over a spindle drive 15 a and/or 17 a so that they move aframe geometry which carries the particular continuous belt sheetconveyor and is movable with respect to a main frame.

Just as the upper sheet conveyor 10 is driven by an electricallycontrolled drive device 16, an upper belt drive 16 a and an upper shaft16 w (see FIGS. 1 and 2), the lower sheet conveyor 11 is also driven bya drive mechanism 18 and a belt drive 18 a on a shaft 18 w situated atthe rear. The rotational motion of the motors 16 and 18 is controlled asneeded by the y forward movement during machining. The drive motors 15,17 of the spindle drives 15 a, 17 a are also triggered incrementallyduring the machining in the tool area W as needed by the x movement. Thetwo movements are superimposed for the upper sheet feed and the bottomsheet feed so that these sheet feeds are not active simultaneously butinstead they are active one after the other.

A first sheet conveyed to the bottom sheet feed 11, for example, resultsin the upper sheet feed 10 with its conveyor belts being free to receivethe next sheet and keep it in a ready position. Since the conveyor beltsare designed to apply forces acting in the z direction (e.g.,magnetically), the second sheet may also be held suspended on the bottomside of the upper conveyor belt 10 in the ready position until thebottom sheet of the bottom sheet feed 11 has been worked by the tool.Then the top sheet feed conveys and positions the next sheet formachining in the tool and the bottom sheet feed 11 picks up the nextsheet and keeps it in the ready position. The transfer of the respectivesheet to the upper or lower conveyor is controlled by the switch 9 byvarying the position thereof.

A rail system is provided with which both sheet feeds can be insertedand retracted. The insertion and retraction pertain to the movement of asupporting main frame on rails or tracks in the direction toward thetool zone W and away from it. This is shown in FIG. 3 for the sheet feedat the input and in FIG. 5 for the sheet feed at the output. Due to apossible stoppage of the input from the working zone and stopping of theoutput from the same working zone which is also possible, the tool whichis provided in the working zone is therefore accessible directly fromboth sides. To allow the movement, tracks or rails 41 a are provided ona base 41 and sliders 41 a′ slide on the rails to permit a movement ofthe supporting frame 41 b on which the entire arrangement rests withrespect to the rails 41 a and with respect to the working zone W. Thesame thing is also provided for the feed at the output. The base 41 hereis the same foundation on which the rails 44 a rest, guiding the slidingpieces 44 a′ on the bottom side of a supporting main frame 44 b, 45. Forprecise positioning, a stop may be provided on the inside end of therails 44 a for stopping the supporting frame 44 b in its end positionclosest to the working zone W.

The movement in the x direction is implemented in the design through aframe construction which is displaceably guided in this direction withrespect to a frame construction 41 c which is not displaceable above abottom frame 41 b. The top part 42 of the intermediate frame 41 c can beopened with respect to the bottom part via a hinge 42 a and the liftingcylinder 19 for maintenance purposes. The displaceable frameconstruction is a system of transverse struts and guides for the upperdrive device 15 like the lower drive system 17. For the sake ofstandardization, the upper guidance system for the belt drive 10 is tobe described with a direct transferability to the lower drive system 17whereby the indices are each transferable, e.g., the upper element 15 acorresponds to the lower element 17 a, etc. The upper spindle drive 15 atranslates its movement to struts 15 f which are situated in the xdirection, two of which are shown here having a width in the transversedirection which spans at least some of the conveyor belts. Perpendicularto that are additional struts 15 d which are spaced a uniform distanceapart, each being arranged between two belts and outside of the edge ofthe outermost belt. These longitudinal struts 15 d are supported withsliding blocks 15 c on supporting frames 15 b on which they can slide,prompted by the movements transmitted by the drive device 15 over thespindle drive 15 a and the transverse struts 15 f to the belt system 10.In these movements the longitudinal drive 16 is not moved with them butinstead the shaft 16 w moves in the axial direction, guided in pinionsor drive rollers which are axially immovable. They are triggered by thedrive 16 with the belt drive 16 a.

The same thing is also true of the lower longitudinal drive 18 with thelower belt drive 18 a and the lower groove shaft 18 w. The same thing isalso true in a corresponding transmission of the drive elements 15 forthe lower drive elements 17, 17 a, 17 b, 17 c and 17 d and/or 17 f.

The design of the conveyor device in the output zone of the tool isillustrated in FIGS. 5 and 6. FIG. 5 shows the view as seen from thetool side. A frame 44 b, 45 carries the table of multiple adjacent beltconveyors 20 a through 20 k which can be moved in direction x. A shaft26 w is provided and can be induced to execute a controlled rotatingmotion jointly by a controlled drive 26 with a belt 26 a so that amovement in direction y can be executed step by step. This rotationalmovement is synchronized with the rotational movement of the sheet feed10 or 11 in the input area of the tool which is conveying the sheets tothe tool, namely drive 16 or 18 there.

The sheet feed 20 also has magnetic surfaces on the individualcontinuous belts 20 a through 20 k which can apply forces in the zdirection, for example, and therefore, like the forces in the zdirection, it can also apply forces to a sheet, in particular a metallicsheet.

The indexing movement in the x direction is achieved by a controlledmotor 27 and a spindle drive 27 a in relation to the frame 45. Thismovement in the x direction is also synchronized with the movement overthe spindle drives 15, 15 a or 17, 17 a in front of the tool. The drivesystem in the x direction for the feed is likewise designed as describedwith respect to the drive elements 15. With the same indices, thesedrive elements are accordingly labeled as 27, based on the controlledmotor 27; 27 f refers to the transverse struts with which the indexingmovement is transmitted from the spindle drive 27 a to the continuousbelts 20. Longitudinal struts 27 b are provided in the longitudinaldirection with continuous belts arranged between or outside of them,sliding on sliding blocks 27 c which are arranged on the supportingrails 27 b. The supporting rails 27 c are not displaceable with respectto the frame 45 which is itself in turn displaceable on the longitudinalrails 44 a for better axis to the tool area but not during the operationof the conveyor.

The output is also depicted according to FIG. 6 in a side view where theplane 100 represents the continuation of the plane 100 in FIG. 4directed toward the tool zone W. Above the support region which isapproaching in a wedge shape, a flat discharge system 29 is provided,forming a gap with the top side of the conveyor belts 20 a through 20 kand supporting the discharge channels 31 a through 31 e. The belt 33which is held by the supporting device 32 runs perpendicularly; it mayalso be magnetic to hold the rounds that have been punched out upwardand convey them away laterally in the transverse direction q, asdepicted in FIGS. 1 and 2.

A sheet conveyed into the tool zone is gripped by the sheet conveyor 20in the output even before the last working operation by gripping it onthe last row which is close to the read edge 1 r of FIG. 8, then it isheld there and is moved in synchronization with the movement of theinlet conveyor belts 10 or 11, depending on which is supplying thesheets at that moment. Since the sheet feed ends in the input zone ofthe machine upstream from the table 52 to provide it with a slightsafety distance, the output conveyor can assume the function of theinput conveyor even before the last stroke is executed for the lastpunching operation. The remaining grid after the rounds have beenpunched out is mechanically strong enough for this to be able to absorbtensile forces for conveying it outward.

FIGS. 1 through 3 show the position and location of sensors 28 (28 aabove, 28 b at the bottom), which are arranged on the input sheet feed10 or 11 in such a way that the position 1″ from FIG. 2 is reliablydiscernable with respect to the sheet 1. An inductive proximity sensorhas proven advantageous for this; it may be mounted beneath the planeformed by the surfaces of the belts. Its distance from the tool in thedirection y is determined by the initial position of the sheets. If thesensor 28 detects the presence of a sheet, the drive 16 or 18 switchesoff, generating the forward movement in the y direction for the feed 10or 11 affected in each case. If the previous sheet has been completelyworked, then it is possible to start immediately following it from thereadiness position, with only a slight gap remaining between the rearedge 1 r of the preceding sheet and the front edge 1 v of the new sheetso that the next sheet is already present in the tool zone before thenext ram stroke triggers the next working operation in a practicallycontinuous process. Thus the feed process does not require any blankstrokes of the tool device 50 which continues to operate at a constantfrequency.

Since the force applied to the sheet is not initiated from an edge butinstead is initiated essentially over the entire area, i.e., bystrip-shaped belt devices, therefore the supporting force is appliedfrom the flat side of the sheets. The forward force is also applied fromthe flat side so that corrugations or deformations can be reliablyprevented at higher feed rates.

In the input, the length of the sheet section supported by the inputsheet feed changes in favor of a greater length in the output. Thesupporting function in the input thus changes the supported area on theflat side of the sheet based on the total area of the sheet. This is nota spot introduction of force which is transmitted at one or two smallspots but instead is an essentially flat transmission over a large areabut it need not be over the full area.

Depending on the distance of the wedge-shaped approaching ends of thefeed mechanism 10, 11 in the input zone and the feed mechanism in theoutput zone, each based on the tool zone, the number of flat pieces Rwhich are worked is determined, while only the output feed 20 isengaged. This residual sheet length may be between 1½ rows and 3 to 4rows, depending on the size of the flat pieces as rounds.

The length of the sheet feed 20 in the output zone may be shorter thanthat in the input zone since the entire sheet need not ever be supportedin the output zone but instead only a small portion of its length needbe supported. In any case, the output conveyor is already active,however, before the last ram stroke has machined the last row Rn of flatpieces. The conveyor device in the output is not only an element forremoving a residual grid from the working zone immediately after thelast working stroke but instead is a feed mechanism which also operateswith the input sheet feeder in a controlled manner but only in theoutput zone of the tool.

1. A feed mechanism for sheets of sheet metal to feed multiple sheetsinto and through a working zone wherein the sheets are machinedcomprising: said feed mechanism having a first and a second sheet feeder(10, 11; 20) for controlling feeding of the sheets to the working zone(W) to machine each of said sheets accurately positioned in the workingzone, each of the sheet feeders having multiple continuous systemsadapted to be synchronously driven in a longitudinal direction in eachof said sheet feeders, and moveable jointly in a transverse direction(x) in a controlled manner for advancing each of the sheets and alsoaccurately position each of the sheets in the working zone; wherein thefirst sheet feeder (10, 11) is arranged on an input side of the workingzone and the second sheet feeder (20) is provided on an output side ofthe working zone, the first and second sheet feeders being synchronizedwith one another in movements thereof (x, y) when feeding each of thesheets (1) through the working zone; whereby each of the sheetsentrained by the synchronous movements is held by the two sheet feeders.2. The feed mechanism according to claim 1, whereby the feed movement ofthe two sheet feeders is composed of common movement sections in saidlongitudinal direction (y) and in said transverse direction (x), whereinmovements in the transverse direction are mainly for positioning andmovements in longitudinal direction are mainly for feeding.
 3. The feedmechanism according to claim 1, whereby the sheet feeder (20) situatedon the output side of the working zone (W) receives each sheet that hasbeen machined and supports it for guiding it in synchronization with themovements (x, y) of the sheet feeder on the input side, even before alast row of rounds (Rn) has been machined by a tool in the working zone.4. The feed mechanism according to claim 1, whereby another sheet feeder(10) for feeding sheets is arranged on the input side of the workingzone and above the first sheet feeder and alternately with the firstsheet feeder feeds sheets (1) to the working zone and to the secondsheet feeder to prevent idle strokes of a working device in the workingzone.
 5. The feed mechanism according to claim 1, the machining is oneof punching out rounds, shaping punched-out rounds or altering thesurface of the sheets.
 6. The feed mechanism according to claim 3,wherein the output side sheet feeder is adapted to receive and support aremaining grid that remains after punching out rounds from a machinedsheet.
 7. The feed mechanism according to claim 3, the tool for themachining is punching out the rounds row by row.
 8. The feed mechanismaccording to claim 1, the second sheet feeder at the output side of theworking zone is adapted for supporting a remaining grid after feedingout punching out rounds from a respective sheet in the working zone. 9.A feed mechanism for sheets of sheet metal to feed multiple sheets intoand through a working zone wherein the sheets are machined comprising:said feed mechanism having a first and a second sheet feeder (10, 11;20) for controlling feeding of the sheets to the working zone (W) tomachine each of said sheets accurately positioned in the working zone;wherein the first sheet feeder (10, 11) is arranged on an input side ofthe working zone and the second sheet feeder (20) is provided on anoutput side of the working zone; the first and second sheet feedersbeing synchronized with one another in movements thereof in x and ydirections when feeding each of the sheets (1) through the working zone;whereby each of the sheets entrained by the synchronous movements isheld by the two sheet feeders, whereby the first and second sheet feedereach comprises an endless system and each of the sheet feeders is heldby a frame, to be movable in said transverse direction, the x direction,and the endless system is movable in a longitudinal direction, the ydirection, whereby the moving in y direction is caused by first andsecond drive shafts, and controllable motors are provided for causingmovements in x and y directions, the controllable motors not beingmovable.
 10. A feed mechanism for sheets of sheet metal to feed multiplesheets into and through a working zone wherein the sheets are machinedcomprising: said feed mechanism having a first and a second sheet feeder(10, 11; 20) for controlling feeding of the sheets to the working zone(W) to machine each of said sheets accurately positioned in the workingzone; wherein the first sheet feeder (10, 11) is arranged on an inputside of the working zone and the second sheet feeder (20) is provided onan output side of the working zone; the first and second sheet feedersbeing synchronized with one another in movements thereof in x and ydirections when feeding each of the sheets (1) through the working zone;whereby each of the sheets entrained by the synchronous movements isheld by the two sheet feeders, whereby at least one stacking area forsheets is arranged laterally in a transverse direction and near to analignment area, positioned upstream from the sheet feeders, whereby thealignment area and at least one of the sheet feeders is movable along arail system longitudinally passing said at least one stacking area, forshifting said alignment area and said sheet feeder away from saidworking zone without moving said at least one stacking area.